The ruling was a clear win for the Mobile couple, Cari Searcy and Kim McKeand, which challenged the law and constitutional amendment that had reserved the institution for heterosexual couples.

But the decision also raises a number of questions. Here are seven of them:

1. Can gay Alabamians apply for marriage licenses on Monday?

A lot depends on how Granade rules on a request that the Alabama Attorney General's Office filed late Friday. Attorneys for the state asked Granade to "stay," or put on hold, her order until after the U.S. Supreme Court determines whether states have the right to define marriage as between one man and one woman.

Attorneys argued that the state is likely to win on appeal.

"In addition, if the action is not stayed, Defendant and the State of Alabama will suffer irreparable harm if marriages are recognized on an interim basis that are ultimately determined to be inconsistent with Alabama law, resulting in confusion in the law and in the legal status of marriages," they wrote.

It is not uncommon for judges to put their rulings on hold in controversial cases if doing so would not significantly injure the prevailing party. It is anyone's guess what Granade will do here or when she might rule. Before then, it is possible that gay couples might try to apply for marriage licenses. And it also is unclear how county probate officials county to county might react to that.

The judge ruled that the ban violates the Due Process Clause and Equal Protection Clause of the 14th Amendment. Basically, that means that the government cannot treat one group of citizens differently from another group of similarly situated citizens without a "compelling" interest.

The Attorney General's Office offered several interests, focusing primarily on the state's goal of promoting the relationship between children and their biological parents. But Granade did not find them persuasive.

She cited several key court cases, including United States v. Windsor, the 2013 case in which the Supreme Court struck down the parts of the federal Defense of Marriage Act. The justices ruled that the federal government could not deny benefits to same-sex couples married in states where same-sex marriage is legal.

The court stopped short of voiding state same-sex marriage laws, but a succession of federal judges across the country have interpreted Windsor to mean exactly that.

In written arguments, the state relied heavily on Baker v. Nelson, a 1972 case in which the Minnesota Supreme Court upheld a ban on gay marriage. The Attorney General's Office noted that the U.S. Supreme Court allowed that ruling to stand and never has invalidated it. But Granade wrote that subsequent Supreme Court rulings reflect "doctrinal developments" since then.

3. In how many states is same-sex marriage still illegal?

An ever-shrinking number. According to Freedom to Marry, same-sex marriage is legal in 35 states. Alabama joins six other states - South Dakota, Texas, Missouri, Arkansas and Louisiana - that are fighting court rulings striking down same-sex marriage bans. Three states - Georgia, North Dakota and Nebraska - have had no court rulings invalidating bans.

That leaves four more states - Michigan, Ohio, Kentucky and Tennessee - in which the 6th U.S. Circuit Court of Appeals reversed lower court rulings striking down marriage bans.

The U.S. Supreme Court this month announced that it would review that ruling, setting up a decision that either will make gay marriage legal in all 50 states or restore dozens of state laws prohibiting those unions.

4. Was the case difficult or complicated?

Not particularly, judging from the brevity of the ruling. When the highest state court in Massachusetts made that state the first in the country to recognize same-sex marriages in 2003, the opinion was 50 pages. In Iowa six years later, the state Supreme Court took 69 pages. A Pennsylvania federal judge wrote 39 pages.

By contrast, Granade's decision was just 10 pages.

The judge held no hearings and took no live testimony. She ruled from the legal briefs that both sides filed.

Granade had the benefit of dozens of same-sex court rulings already on the books, and she hinted that much of the legal ground already had been plowed.

5. How does this decision affect two other same-sex marriage cases pending in Alabama?

Nothing directly. But if Granade's decision stands and Alabama's same-sex stands, it could short-circuit cases currently pending in federal courts in Birmingham and Montgomery.

In the Montgomery case, Paul Hard seeks to inherit the proceeds of a wrongful-death lawsuit filed by the estate of Charles David Fancher, whom he married legally in Massachusetts. In the Birmingham case, April and Ginger Aaron-Brush seek to have their 2012 wedding in Massachusetts recognized in Alabama.

6. What is the background of the judge who made the ruling?

Granade was a longtime federal prosecutor when then-President George W. Bush tapped her in 2001, for a seat on the bench. The Senate confirmed her in 2002. She had the support of U.S. Sen. Jeff Sessions, R-Mobile, who had been her boss when he was U.S. attorney in the Reagan administration.

She had a reputation as a tough-minded prosecutor and has carried that demeanor to the bench.

Her ruling on the gay marriage issue is in keeping with the national trend - jurists across the ideological spectrum, appointed by presidents from both parties, mostly have lined up on the same side of this issue.

"I understand how painful it can be for the state to tell you that your marriage is inferior in the eyes of the law. I am elated that other couples will no longer feel that pain." -- Paul Hard, plaintiff in the Montgomery case.

"It's a historic day. I can't tell you how ecstatic I am. Lots and lots of people can celebrate their love today." - State Rep. Patricia Todd, D-Birmingham, Alabama's first openly gay legislator.

"As the U.S. Supreme Court prepares to hear a landmark case on marriage equality, today's ruling joins the dozens and dozens of others that have recognized that committed and loving gay and lesbian couples deserve equal treatment under the law." - Human Rights Campaign Legal Director Sarah Warbelow

"We are disappointed and are reviewing the Federal District Court's decision. " - Mike Lewis, spokesman for Attorney General Luther Strange.

"This federal judge is throwing out the votes of the people of Alabama and attempting to shut down the debate over marriage. In exercising their right to vote, Alabama voters overwhelmingly sent a message that that they want to see society rebuild and strengthen marriage - not have it redefined by unelected judges." - Family Research Council President Tony Perkins.

"Tonight's news is a clear demonstration of how traditional values espoused by Alabamians have begun to erode even in our conservative state. The far left-wing radical agenda of Barack Obama and the Democratic Party have brought to Alabama's front door their effort to redefine marriage. - Alabama Republican Party Chairman Bill Armistead.

Updated at 3:12 p.m. on Jan. 25 to correct the year in which Loving v. Virginia was decided.